<template>
<div class="s-canvas">
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
</div>
</template>
<script>
export default{
name: 'Authcode',
props: {
    identifyCode: { // 默认注册码
    type: String,
    default: '1234'
    },
    fontSizeMin: { // 字体最小值
    type: Number,
    default: 25
    },
    fontSizeMax: { // 字体最大值
    type: Number,
    default: 35
    },
    backgroundColorMin: { // 验证码图片背景色最小值
    type: Number,
    default: 200
    },
    backgroundColorMax: { // 验证码图片背景色最大值
    type: Number,
    default: 220
    },
    dotColorMin: { // 背景干扰点最小值
    type: Number,
    default: 60
    },
    dotColorMax: { // 背景干扰点最大值
    type: Number,
    default: 120
    },
    contentWidth: { // 容器宽度
    type: Number,
    default: 90
    },
    contentHeight: { // 容器高度
    type: Number,
    default: 38
    }
},
methods: { 
    // 生成一个随机数
    randomNum (min, max) {
    return Math.floor(Math.random() * (max - min) + min)
    },
    
    // 生成一个随机的颜色
    randomColor (min, max) {
    let r = this.randomNum(min, max)
    let g = this.randomNum(min, max)
    let b = this.randomNum(min, max)
    return 'rgb(' + r + ',' + g + ',' + b + ')'
    },
    
    drawPic () {
    let canvas = document.getElementById('s-canvas')
    let ctx = canvas.getContext('2d')
    ctx.textBaseline = 'bottom'
    // 绘制背景
    ctx.fillStyle = '#e6ecfd'
    ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
    // 绘制文字
    for (let i = 0; i < this.identifyCode.length; i++) {
    this.drawText(ctx, this.identifyCode[i], i)
    }
    this.drawLine(ctx)
    this.drawDot(ctx)
    },
    
    drawText (ctx, txt, i) {
    ctx.fillStyle = this.randomColor(50, 160) // 随机生成字体颜色
    ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei' // 随机生成字体大小
    let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
    let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
    var deg = this.randomNum(-30, 30)
    // 修改坐标原点和旋转角度
    ctx.translate(x, y)
    ctx.rotate(deg * Math.PI / 180)
    ctx.fillText(txt, 0, 0)
    // 恢复坐标原点和旋转角度
    ctx.rotate(-deg * Math.PI / 180)
    ctx.translate(-x, -y)
    },
    
    drawLine (ctx) {
    // 绘制干扰线
    for (let i = 0; i < 4; i++) {
    ctx.strokeStyle = this.randomColor(100, 200)
    ctx.beginPath()
    ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
    ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
    ctx.stroke()
    }
    },
    
    drawDot (ctx) {
    // 绘制干扰点
    for (let i = 0; i < 30; i++) {
    ctx.fillStyle = this.randomColor(0, 255)
    ctx.beginPath()
    ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
    ctx.fill()
    }
    }
},
watch: {
    identifyCode () {
    this.drawPic()
    }
},
mounted () {
    this.drawPic()
}
}
</script>
<style scoped>

</style>
   